IE10 Compat Inspector

Compat Inspector is now available
for IE10. Use Compat Inspector to quickly identify if Internet Explorer platform changes affect your site. Whether you're
preparing for IE10 or still updating for IE9, run Compat Inspector on any page experiencing problems. Then watch for messages
explaining potential issues and steps you can take to resolve them.

About Compat Inspector

Compat Inspector is a JavaScript-based testing tool that analyzes your site while it runs. Compat Inspector reports patterns
of interaction which cause issues in recent modes. This allows you to identify problems quickly without memorizing a bunch
of documentation or searching through the entirety of your site's code. We developed Compat Inspector during the course
of IE9 to speed up the process of recognizing common issues across different sites and have now updated it for IE10. Along
the way, many members of the IE team contributed to the set of test cases that make up the rules in Compat Inspector.

Compat Inspector is designed to help sites migrating to IE9 or IE10 mode—not those running in legacy modes.
You can test sites that run in legacy modes by selecting a more recent mode via the F12 developer tools.
Just press F12 to open the tools, click on "Document Mode" in the menu bar, then select "Standards".
You may need to refer to more detailed documentation such as the
IE9 Compatibility Cookbook or the
IE10 Developer Guide for some issues. The best pattern is to use Compat Inspector
first, then fall back to the documentation if nothing is found.

Using Compat Inspector

Run Compat Inspector by adding the following script before all other scripts on each page you want to test (the need to run before other scripts means Compat Inspector can't be used as a bookmarklet):

This will place a status widget in the upper right hand corner of the page. Click the widget to get more information.

You can streamline this process by using Fiddler to automatically inject Compat Inspector
on pages you visit. Just add
this snippet to your
Fiddler Script to get up and running. This configuration also automatically inspects all sub-frames in a page.
Once the snippet is in place you can toggle Compat Inspector on and off from Fiddler's "Rules" menu.